Downhole exploration and production efforts involve a large number of sensors and measurement systems that provide information about the downhole environment. The downhole efforts fall into various categories that each involves different types of wells. Two main categories or phases of operation involved in well construction are drilling and completion. Drilling involves forming the well while completion involves readying the well using piping and storage apparatus. While the borehole walls may be bare during drilling, a (cement) casing is typically disposed downhole as part of the completion process to prevent collapse of the well walls, for example. In some downhole (e.g., subsea) completions, a first casing may be cemented to the well walls and a second casing may be hung inside. Tubing is introduced inside this second casing and is used for production. While sensors and measurement devices are commonly used in the annulus between the second casing and the tubing, monitoring conditions in the annulus between the first casing and the second casing may be more challenging.